Inertia operated switch



. 1, 1959 J. RABINOW ETAL 2,915,604

INERTIA OPERATED SWITCH 2 Sheets-Sheet 1 Filed Feb. 16, 1944 INVENTORS JACOB RAB/NOW BY LAURE/VG} W8 7/ AT Y 4 United States Patent INERTIA OPERATED SWITCH Jacob Rabinow and Laurence M. Andrews, Washington, 1D.C.,'assignors to the United States of America as represented by the Secretary of the Navy Application February '16, 1944, Serial No. 522,612

7 Claims. (Cl. ZOO-61.45)

(Granted under Title 35, US. Code (1952), sec. 266) This invention relates to circuit making and breaking devices and more particularly to an inertia-operated switch for use with an electrical device, such as a fuze, 1n a I projectile.

One object of the invention is to provide an inertiaoperated device having three switches and means including a spring for successively operating one of the switches, closing the second switch momentarily and then operatlng the third switch.

Another object of the invention is to provide an inertiaoperated device in which a weight is moved by the force of inertia to close a pair of switches, the weight then being moved by a spring to open one of the switches and close a third switch.

A further object of this invention is to provide a device of the character described which will operate only uponsustained acceleration and which will not be operated accidentally, as by dropping or jolting.

These and further objects will be apparent from the following description and the accompanying drawings, in which Fig. 1 is a side elevation of one embodiment of the invention for use in a projectile fuze, showing the parts in their initial positions with the switches open;

Fig. 2 is a cross sectional view on the line 2-2 of Fig. 1; j v

Fig. 3 is a view similar to Fig. 1 but with the parts in their intermediate positions after actuation by inertia and before the Weight has been actuated by the spring;

Fig. 4- is a cross sectional view on line 4-4 of Fig. 3;

Fig. 5 is a view similar to Figs. 1 and 3 but with the parts in their final position;

Fig. 6 is a sectional view on line 6-6 of Fig. 5;

Figs. 7 and 8 are sectional views on lines 7-7 and 8-8,

respectively, of Fig. 1;

Fig. 9 is a fragmentary cross sectional view on line 9-9 of Fig. 3, and

Fig. 10 is a perspective view of the weight which is moved by inertia.

' In the drawings, the device as shown comprises a plate 20 which supports a nonconducting member 22 by means of screws 21 or other suitable means. The member 22 carries a plurality of electrical contact members 23, 24, 25 and 26 mounted on the front thereof, and also a pair of contact members 26:: (Fig. 7) mounted on the rear thereof.

On the upper portion of plate 20 is a stub shaft 27 which carries an escapement wheel 28 having pins 29 and 29:: on its rear face. A second'shaft 30 is mounted on the central-portion of plate 20 and carries a sleeve 31 rotatably mounted thereon. A notched wheel segment 32 is mounted on sleeve 31 for rotation with the sleeve and is so proportioned and positioned that the notches thereon cooperate with pins 29 and 29a to form an escapement. A disk 33 of nonconducting material is mounted on sleeve 31 for rotation therewith and has a switch arm 34 which is positioned on disk 33 so as to bridge contact members 26 1 when disk 33 is rotated to the proper position.

A second sleeve 35 is rotatably mounted on shaft 30 beyond sleeve 31 and carries a weight 36. Also mounted on and rotatable with sleeve 35 is disk 37 made of insulating material. Switch arms 38 and 39 are secured to disk 37 and are so positioned thereon as to bridge contact members 23-24 and 25-26, respectively, upon rotation of the disk, as will be explained presently. Held in a keyway 40 at one end of shaft 30 is a spring 41 which is attached to weight 36 by means of a pin 42. This spring exerts a force on weight 36 tending to rotate the Weight in a clockwise direction as viewed in Fig. 1.

The weight 36 has a shoulder 43 (Fig. 10) which abuts a resilient latching member 44 mounted on the notched wheel segment 32. The resilient member 44, as shown in Fig. 8, comprises a portion bent back upon itself at 45 to form a straight portion 46 which extends through an opening 47 in the notched wheel segment 32. An opening 48 in the lower portion of plate 20 receives the end ofv the straight portion 46 of resilient member 44 when the wheel 32 reaches the proper position, as will be explained presently.

The operation of the device will now, be explained. In Fig. 1, the parts are shown in their positions before the switch is accelerated. The notched wheel segment 32 is at the limit of its clockwise movement, as pin 29a is against the enlarged tooth at the end of the notched portion of the wheel. Weight 36 abuts an upturned portion 32a of the wheel segment and is thus prevented from moving counterclockwise relative to the wheel segment. Shoulder 43 of the weight abuts the resilient latch member 44 on the wheel segment 32, thus preventing weight 36 from moving clockwise relative to the wheel segment. The force of the spring 41 prevents counterclockwise rotation of the parts except on substantial acceleration. When the parts of the switch are in their positions shown in Fig. 1, all of the switch arms are in their open circuit positions.

On sustained acceleration of the switch in the direction of the arrow in Fig. 1, the force of inertia acting on weight 36 rotates the weight in a counterclockwise direction against the spring 41 to the position shown in Fig. 3. Since the weight engages the turned-up edge 32a of the notched wheel 32, rotation of the weight causes the notched wheel to rotate with the weight. This rotation, is retarded by the escapement action of the notched portion of the wheel 32 cooperating with pins 29 and 29a of the escapement wheel 28. The provision of the escapement prevents actuation of the celeration, such as by jolting or dropping of the projectile containing the switch. It will be apparent that if the Weight 36 is rotated through a part of its range by such unsustained acceleration, the spring 41 will return the weight to its initial position immediatelty upon termination of the acceleration, and the weight by its engagement with latch 45 will return the wheel 32 to its initial position.

When the weight 36 and wheel segment 32 reach the positions shown in Fig. 3, their counter-clockwise rotation is halted by the edge portion 32a striking one of the screws 21 or other detent means. On reaching this position, the straight portion of resilient latch 44 is disposed above the opening 48 in plate 20 and is moved into the opening 48 by the resiliency of latch 44, as shown in Fig. 9. Thereupon, the bent-over portion 45 of the resilient latch, which until this moment has prevented clockwise rotation of the weight 36 relative to the wheel seg ment 32 by engaging the shoulder 43 on the weight, moves clear of the shoulder 43, thus freeing weight 36 for clockwise movement under the influence of spring 41.

When the wheel segment 32 and disk 33 reach the limit of their counter-clockwise rotation, the switch arm 34 on the disk bridges contacts 26a on insulating member 22 to complete the circuit across contacts 26a. Due to the fact switch by unsustained ac- 3 that the resilient latch 44 locks the wheel segment 32 in this position by projecting into opening 48, the circuit remains closed.

When the weight 36 is at the limit of its counterclockwise rotation, switch arm 39 on disk .37 bridges contacts 25 and 26 to complete a circuit across those contacts. Upon unlatching of the weight 36 from the wheel segment, as previously described, and upon termination of the sustained acceleration, spring 41 moves the weight 36 and disk 37 to the position shown in Fig. 5, thus moving switch arm 39 away from contacts 25 and .36 and breaking their circuit.

When weight 36 reaches the position shown in Fig. 5, under the action of spring 41, it is halted due to the fact that shoulder 43 on the weight engages escapement wheel 28. In this position of the weight and its disk 37, the switch arm 38 on disk 37 bridges contacts 23 and 24, thus completing the circuit across those members. Since the spring holds the weight in its final position (Fig. the circuit of contacts 23, 24 remains closed by arm 38.

The switch of our invention may be used for various purposes in electrical devices subjected to inertia. For example, it may be employed in an electrically operated projectile fuze having an electronic device, in which case the contacts 2.6a may be included in a battery circuit to connect in the battery as soon after firing the projectile as the escapement permits, and the contacts 23 and 24 may be included in a thyratron or other relay circuit controlling the fuze detonator. Since the contacts 2324 cannot be closed to arm the switch until after the con tacts 26a are closed, premature explosions resulting from the shock of firing or from rough handling are avoided. The contacts 2526 are closed for only a brief period between the time when the weight reaches its inertiaactuated position (Fig. 3) and the time when the inertia has dissipated sufliciently to permit the spring 41 tornove the weight back toward its initial position. The contacts 25-26 may be used in a circuit which is to be closed only temporarily, as, for example, in a short circuit for the detonator to prevent accidental energizing thereof when the battery is first connected.

The emodiment of the device shown in the drawings and described above is particularly adapted for use in a non-rotating projectile but our invention is not limited to use in such projectiles.

The invention herein described may be manufactured and used by or for the Government of the United States I of America for governmental purposes without the'payment of any royalties thereon or therefor.

We claim:

1. In an inertia-operated device, a weight movable by a force of setback upon acceleration of the device, three switches, means movable by said weight in response to setback to operate one of said switches, biasing means opposing said movement of the weight, and means movable by said biasing means upon operation of said first switch for successively operating the other two switches.

2. In an inertia-operated device, a weight movable by a force of setback upon acceleration of the device, three switches, a member for operating one of said switches, means for latching said member to the weight to cause the weight to actuate said member in response to set back, said latching means being operable to release the weight from said member upon movement of said mem her to its switch-operating position, biasing means for opposing movement of the weight, and means operable by said biasing means upon operation of said first switch for successively operating the other two switches.

3. In an inertia-operated device, a weight movable by a force of inertia on acceleration of the device, three switches, a member for operating one of said switches, means for latching said member to the weight to cause the weight to actuate said member in response to inertia, said latching means being operable to release the weight from said memberupon movement of said member to its switch-operating position and simultaneously to latch said first-named member in its closed circuit position, biasing means for opposing movement of the weight, and means operable by said biasing means upon operation of said first switch for successively operating the other two switches.

4. In an inertia-operated device, a weight movable'by a force of inertia on acceleration of the device, three switches, means movable by said weight in response to inertia to operate one of said switches, a spring opposing said movement of the weight, and means operable by said spring upon operation of said first switch for succes sively operating the other two switches.

5. In an inertia-operated device, a weight movable by a force of inertia on acceleration of the device, three switches, a notched escapement wheel latched to and movable with said weight in response to inertia to operate the first of said switches, means movable with the weight for operating the other two switches, means for unlatching said weight from said wheel on completion of said movement, and a spring opposing said movement of the weight and acting to move said weight after un latching to operate thesecond switch and .the third switch successively.

6. In an inertia-operated device, a weight mounted for rotation by the force of inertia on acceleration of the device, three pairs of contacts, a switch arm rotatable with said weight and positioned to bridge one pair of said contacts upon movement of the weight by inertia, an escapement wheel latched to and rotatable with said weight, a switch arm rotatable with said wheel and positioned to bridge the second pair of contacts on rotation of said wheel with said weight, means for unlatching said weight from said wheel after completion of their inertia actuated movement, a third switch arm rotatable with said weight, and a spring opposing said movement of the weight and acting upon unlatching of the weight to rotate said weight whereby said first-mentioned switch arm is rotated to open the circuit across its correspond ing pair of contacts and said third switch arm is rotated to close a circuit across the third pair of contacts.

7. In an inertia-operated device, a weight movable by a force of setback upon acceleration of the device, three switches, means movable by said weight in response to setback to operate two of said switches, biasing means tending to operate the third switch, and means movable by said biasing means upon operation of said two switches and upon substantial cessation of the acceleration to operate one of said twoswitches a second time and to operate said third switch.

References Cited in the file of this patent UNITED STATES PATENTS 422,524 Happolt Mar. 4, 1890 880,315 Lord Feb. 25, 1908 1,241,520 Jordan Oct. 2, 1917 2,034,649 Brown Mar. 17, 1936 

